Aviation regulators, such as JAR (Joint Aviation Regulation), FAR (Federal Aviation Regulation) and EASA (European Aviation Safety Agency), specify requirements for fixed wing aircraft on the performance and reliability of the hydraulic systems that provide power to the aircraft's wing flight controls throughout the service life of the aircraft.
Hydraulic pipes run through various regions of the aircraft, e.g. along the aircraft wing trailing edge close to the rear structural spar. To help meet the performance and reliability requirements of the hydraulic systems, clamp block assemblies are used to hold, segregate and support the hydraulic pipes off the wing structure, without causing any localised damage to the hydraulic pipe surface in the clamping zone. The pipes are also required to be able to move axially through the clamp blocks due to thermal expansion and bending of the wing.
An existing clamp block assembly design solution comprises two opposing moulded plastic (nylon) blocks scalloped out to accept one or more hydraulic pipes—typically two or three pipes. Attaching and holding the two clamp blocks together are a pair of nut and bolt combinations.
Each nut and bolt combination includes a spacer tube around the bolt that sets the position of the bolt leaving a gap between the bolt head and the nearest nylon block. A spring washer acts against the bolt head and pushes the clamp blocks together. The intent is to allow the hydraulic system to be fitted without applying too much clamping force to the nylon blocks and inadvertently damaging the hydraulic pipes upon installation.
Holding the clamp block assembly in position is an attachment bracket which is also sandwiched within the clamped assembly of the existing solution.
The existing clamp block assembly design suffers the following disadvantages:                No tolerance to any variation in the pipe centre distances (i.e. the distance between the centres of any pair of pipes held within a clamp block), requiring a different clamp block design solution for each distance variation.        No tolerance of any variation in the pipe diameters requiring a different clamp block design solution for each size variation.        Does not promote commonality of parts through self adjustment.        Has high weight, primarily due to the material types.        Has high cost, due to the parts and high tolerance level.        Is sensitive to component tolerance variation.        Is complex and not intuitive to assemble, requiring a high skill set.        